First u have to use a weather changing move like sunny day, that will stop the hail. Give ur strongest pokemon the leftovers.* Don't think you can knockout his pokemon when it has low health. He will surprise you. Attack till the opponent is at half, then launch ur final move. That's how I won

I beat Red using 3 non-uber pokemon, all at level 50, without using medicine of any kind. The key idea was to Trick a Flame Orb to Pikachu (removing its Light Ball at the same time). Now while all my pokemon are immune to Pikachu's electric attacks, and Iron Tail and Quick Attack are 4x weakened due to burn & lack of Light Ball, I take my time to remove the hail, setup Swords Dance, Rock Polish and Stealth Rock, then Baton Pass the stat boosts to my sweeper. All this has to be done before Pikachu faints, or else Red's next pokemon would destroy my heavily under-leveled team. Every move in this set finds its place in the battle, and while Electivire has to have Rock Climb (instead of Earthquake or something), I had to find a way to KO the Pikachu without activating its Static ability. Here's my team, and check out my video at the bottom!